Here's the thing: if we knew the answer definitively to the lab-leak question, how would it change the pandemic response? The things we need to do to combat the virus remain the same.
If you're fighting a shooting war and you have an explosion in a munitions factory, you don't necessarily decide to stop making munitions, or perhaps even that type of munition because it's too dangerous. You make a judgement that balances the risks.
What an apt analogy!
In scientific research particularly, not having seen results yet doesn't mean we should abandon the research. If gain-of-function research is supposed to help us gain a better understanding of viruses and we're likely to see more pandemic-worthy viruses like SARS and SARS-CoV-2 arise naturally, I think any ban should be considered very carefully.
Virologists competing with each other on who can produce the most infectious virus does not make us safer. Pursing research to prove that small pox can indeed mutate to be infectious via airborne aerosols is reckless, it creates a super charged version of a virus that never evolved naturally despite being a common disease for millennia.